patch(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ENVIRONMENT | FILES | SEE ALSO | NOTES FOR PATCH SENDERS | DIAGNOSTICS | CAVEATS | COMPATIBILITY ISSUES | BUGS | COPYING | AUTHORS | COLOPHON

PATCH(1)                 General Commands Manual                PATCH(1)

NAME         top

       patch - apply a diff file to an original

SYNOPSIS         top

       patch [options] [originalfile [patchfile]]

       but usually just

       patch -pnum <patchfile

DESCRIPTION         top

       patch takes a patch file patchfile containing a difference
       listing produced by the diff program and applies those
       differences to one or more original files, producing patched
       versions.  Normally the patched versions are put in place of the
       originals.  Backups can be made; see the -b or --backup option.
       The names of the files to be patched are usually taken from the
       patch file, but if there's just one file to be patched it can be
       specified on the command line as originalfile.

       Upon startup, patch attempts to determine the type of the diff
       listing, unless overruled by a -c (--context), -e (--ed), -n
       (--normal), or -u (--unified) option.  Context diffs (old-style,
       new-style, and unified) and normal diffs are applied by the patch
       program itself, while ed diffs are simply fed to the ed(1) editor
       via a pipe.

       patch tries to skip any leading garbage, apply the diff, and then
       skip any trailing garbage.  Thus you could feed an article or
       message containing a diff listing to patch, and it should work.
       If the entire diff is indented by a consistent amount, if lines
       end in CRLF, or if a diff is encapsulated one or more times by
       prepending "- " to lines starting with "-" as specified by
       Internet RFC 934, this is taken into account.  After removing
       indenting or encapsulation, lines beginning with # are ignored,
       as they are considered to be comments.

       With context diffs, and to a lesser extent with normal diffs,
       patch can detect when the line numbers mentioned in the patch are
       incorrect, and attempts to find the correct place to apply each
       hunk of the patch.  As a first guess, it takes the line number
       mentioned for the hunk, plus or minus any offset used in applying
       the previous hunk.  If that is not the correct place, patch scans
       both forwards and backwards for a set of lines matching the
       context given in the hunk.  First patch looks for a place where
       all lines of the context match.  If no such place is found, and
       it's a context diff, and the maximum fuzz factor is set to 1 or
       more, then another scan takes place ignoring the first and last
       line of context.  If that fails, and the maximum fuzz factor is
       set to 2 or more, the first two and last two lines of context are
       ignored, and another scan is made.  (The default maximum fuzz
       factor is 2.)

       Hunks with less prefix context than suffix context (after
       applying fuzz) must apply at the start of the file if their first
       line number is 1.  Hunks with more prefix context than suffix
       context (after applying fuzz) must apply at the end of the file.

       If patch cannot find a place to install that hunk of the patch,
       it puts the hunk out to a reject file, which normally is the name
       of the output file plus a .rej suffix, or # if .rej would
       generate a file name that is too long (if even appending the
       single character # makes the file name too long, then # replaces
       the file name's last character).

       The rejected hunk comes out in unified or context diff format.
       If the input was a normal diff, many of the contexts are simply
       null.  The line numbers on the hunks in the reject file may be
       different than in the patch file: they reflect the approximate
       location patch thinks the failed hunks belong in the new file
       rather than the old one.

       As each hunk is completed, you are told if the hunk failed, and
       if so which line (in the new file) patch thought the hunk should
       go on.  If the hunk is installed at a different line from the
       line number specified in the diff, you are told the offset.  A
       single large offset may indicate that a hunk was installed in the
       wrong place.  You are also told if a fuzz factor was used to make
       the match, in which case you should also be slightly suspicious.
       If the --verbose option is given, you are also told about hunks
       that match exactly.

       If no original file origfile is specified on the command line,
       patch tries to figure out from the leading garbage what the name
       of the file to edit is, using the following rules.

       First, patch takes an ordered list of candidate file names as
       follows:

        If the header is that of a context diff, patch takes the old
          and new file names in the header.  A name is ignored if it
          does not have enough slashes to satisfy the -pnum or
          --strip=num option.  The name /dev/null is also ignored.

        If there is an Index: line in the leading garbage and if
          either the old and new names are both absent or if patch is
          conforming to POSIX, patch takes the name in the Index: line.

        For the purpose of the following rules, the candidate file
          names are considered to be in the order (old, new, index),
          regardless of the order that they appear in the header.

       Then patch selects a file name from the candidate list as
       follows:

        If some of the named files exist, patch selects the first name
          if conforming to POSIX, and the best name otherwise.

        If patch is not ignoring RCS, ClearCase, Perforce, and SCCS
          (see the -g num or --get=num option), and no named files exist
          but an RCS, ClearCase, Perforce, or SCCS master is found,
          patch selects the first named file with an RCS, ClearCase,
          Perforce, or SCCS master.

        If no named files exist, no RCS, ClearCase, Perforce, or SCCS
          master was found, some names are given, patch is not
          conforming to POSIX, and the patch appears to create a file,
          patch selects the best name requiring the creation of the
          fewest directories.

        If no file name results from the above heuristics, you are
          asked for the name of the file to patch, and patch selects
          that name.

       To determine the best of a nonempty list of file names, patch
       first takes all the names with the fewest path name components;
       of those, it then takes all the names with the shortest basename;
       of those, it then takes all the shortest names; finally, it takes
       the first remaining name.

       Additionally, if the leading garbage contains a Prereq: line,
       patch takes the first word from the prerequisites line (normally
       a version number) and checks the original file to see if that
       word can be found.  If not, patch asks for confirmation before
       proceeding.

       The upshot of all this is that you should be able to say, while
       in a news interface, something like the following:

              | patch -d /usr/src/local/blurfl

       and patch a file in the blurfl directory directly from the
       article containing the patch.

       If the patch file contains more than one patch, patch tries to
       apply each of them as if they came from separate patch files.
       This means, among other things, that it is assumed that the name
       of the file to patch must be determined for each diff listing,
       and that the garbage before each diff listing contains
       interesting things such as file names and revision level, as
       mentioned previously.

OPTIONS         top

       -b  or  --backup
          Make backup files.  That is, when patching a file, rename or
          copy the original instead of removing it.  When backing up a
          file that does not exist, an empty, unreadable backup file is
          created as a placeholder to represent the nonexistent file.
          See the -V or --version-control option for details about how
          backup file names are determined.

       --backup-if-mismatch
          Back up a file if the patch does not match the file exactly
          and if backups are not otherwise requested.  This is the
          default unless patch is conforming to POSIX.

       --no-backup-if-mismatch
          Do not back up a file if the patch does not match the file
          exactly and if backups are not otherwise requested.  This is
          the default if patch is conforming to POSIX.

       -B pref  or  --prefix=pref
          Use the simple method to determine backup file names (see the
          -V method or --version-control method option), and append pref
          to a file name when generating its backup file name.  For
          example, with -B /junk/ the simple backup file name for
          src/patch/util.c is /junk/src/patch/util.c.

       --binary
          Write all files in binary mode, except for standard output and
          /dev/tty.  When reading, disable the heuristic for
          transforming CRLF line endings into LF line endings.  This
          option is needed on POSIX systems when applying patches
          generated on non-POSIX systems to non-POSIX files.  (On POSIX
          systems, file reads and writes never transform line endings.
          On Windows, reads and writes do transform line endings by
          default, and patches should be generated by diff --binary when
          line endings are significant.)

       -c  or  --context
          Interpret the patch file as a ordinary context diff.

       -d dir  or  --directory=dir
          Change to the directory dir immediately, before doing anything
          else.

       -D define  or  --ifdef=define
          Use the #ifdef ... #endif construct to mark changes, with
          define as the differentiating symbol.

       --dry-run
          Print the results of applying the patches without actually
          changing any files.

       -e  or  --ed
          Interpret the patch file as an ed script.

       -E  or  --remove-empty-files
          Remove output files that are empty after the patches have been
          applied.  Normally this option is unnecessary, since patch can
          examine the time stamps on the header to determine whether a
          file should exist after patching.  However, if the input is
          not a context diff or if patch is conforming to POSIX, patch
          does not remove empty patched files unless this option is
          given.  When patch removes a file, it also attempts to remove
          any empty ancestor directories.

       -f  or  --force
          Assume that the user knows exactly what he or she is doing,
          and do not ask any questions.  Skip patches whose headers do
          not say which file is to be patched; patch files even though
          they have the wrong version for the Prereq: line in the patch;
          and assume that patches are not reversed even if they look
          like they are.  This option does not suppress commentary; use
          -s for that.

       -F num  or  --fuzz=num
          Set the maximum fuzz factor.  This option only applies to
          diffs that have context, and causes patch to ignore up to that
          many lines of context in looking for places to install a hunk.
          Note that a larger fuzz factor increases the odds of a faulty
          patch.  The default fuzz factor is 2.  A fuzz factor greater
          than or equal to the number of lines of context in the context
          diff, ordinarily 3, ignores all context.

       -g num  or  --get=num
          This option controls patch's actions when a file is under RCS
          or SCCS control, and does not exist or is read-only and
          matches the default version, or when a file is under ClearCase
          or Perforce control and does not exist.  If num is positive,
          patch gets (or checks out) the file from the revision control
          system; if zero, patch ignores RCS, ClearCase, Perforce, and
          SCCS and does not get the file; and if negative, patch asks
          the user whether to get the file.  The default value of this
          option is given by the value of the PATCH_GET environment
          variable if it is set; if not, the default value is zero.

       --help
          Print a summary of options and exit.

       -i patchfile  or  --input=patchfile
          Read the patch from patchfile.  If patchfile is -, read from
          standard input, the default.

       -l  or  --ignore-whitespace
          Match patterns loosely, in case tabs or spaces have been
          munged in your files.  Any sequence of one or more blanks in
          the patch file matches any sequence in the original file, and
          sequences of blanks at the ends of lines are ignored.  Normal
          characters must still match exactly.  Each line of the context
          must still match a line in the original file.

       --merge or --merge=merge or --merge=diff3
          Merge a patch file into the original files similar to diff3(1)
          or merge(1).  If a conflict is found, patch outputs a warning
          and brackets the conflict with <<<<<<< and >>>>>>> lines.  A
          typical conflict will look like this:

              <<<<<<<
              lines from the original file
              |||||||
              original lines from the patch
              =======
              new lines from the patch
              >>>>>>>

          The optional argument of --merge determines the output format
          for conflicts: the diff3 format shows the ||||||| section with
          the original lines from the patch; in the merge format, this
          section is missing.  The merge format is the default.

          This option implies --forward and does not take the --fuzz=num
          option into account.

       -n  or  --normal
          Interpret the patch file as a normal diff.

       -N  or  --forward
          When a patch does not apply, patch usually checks if the patch
          looks like it has been applied already by trying to reverse-
          apply the first hunk.  The --forward option prevents that.
          See also -R.

       -o outfile  or  --output=outfile
          Send output to outfile instead of patching files in place.  Do
          not use this option if outfile is one of the files to be
          patched.  When outfile is -, send output to standard output,
          and send any messages that would usually go to standard output
          to standard error.

       -pnum  or  --strip=num
          Strip the smallest prefix containing num leading slashes from
          each file name found in the patch file.  A sequence of one or
          more adjacent slashes is counted as a single slash.  This
          controls how file names found in the patch file are treated,
          in case you keep your files in a different directory than the
          person who sent out the patch.  For example, supposing the
          file name in the patch file was

          /u/howard/src/blurfl/blurfl.c

       setting -p0 gives the entire file name unmodified, -p1 gives

          u/howard/src/blurfl/blurfl.c

       without the leading slash, -p4 gives

          blurfl/blurfl.c

       and not specifying -p at all just gives you blurfl.c.  Whatever
       you end up with is looked for either in the current directory, or
       the directory specified by the -d option.

       --posix
          Conform more strictly to the POSIX standard, as follows.

           Take the first existing file from the list (old, new,
             index) when intuiting file names from diff headers.

           Do not remove files that are empty after patching.

           Do not ask whether to get files from RCS, ClearCase,
             Perforce, or SCCS.

           Require that all options precede the files in the command
             line.

           Do not backup files when there is a mismatch.

       --quoting-style=word
          Use style word to quote output names.  The word should be one
          of the following:

          literal
                 Output names as-is.

          shell  Quote names for the shell if they contain shell
                 metacharacters or would cause ambiguous output.

          shell-always
                 Quote names for the shell, even if they would normally
                 not require quoting.

          c      Quote names as for a C language string.

          escape Quote as with c except omit the surrounding double-
                 quote characters.

          You can specify the default value of the --quoting-style
          option with the environment variable QUOTING_STYLE.  If that
          environment variable is not set, the default value is shell.

       -r rejectfile  or  --reject-file=rejectfile
          Put rejects into rejectfile instead of the default .rej file.
          When rejectfile is -, discard rejects.

       -R  or  --reverse
          Assume that this patch was created with the old and new files
          swapped.  (Yes, I'm afraid that does happen occasionally,
          human nature being what it is.)  patch attempts to swap each
          hunk around before applying it.  Rejects come out in the
          swapped format.  The -R option does not work with ed diff
          scripts because there is too little information to reconstruct
          the reverse operation.

          If the first hunk of a patch fails, patch reverses the hunk to
          see if it can be applied that way.  If it can, you are asked
          if you want to have the -R option set.  If it can't, the patch
          continues to be applied normally.  (Note: this method cannot
          detect a reversed patch if it is a normal diff and if the
          first command is an append (i.e. it should have been a delete)
          since appends always succeed, due to the fact that a null
          context matches anywhere.  Luckily, most patches add or change
          lines rather than delete them, so most reversed normal diffs
          begin with a delete, which fails, triggering the heuristic.)

       --read-only=behavior
          Behave as requested when trying to modify a read-only file:
          ignore the potential problem, warn about it (the default), or
          fail.

       --reject-format=format
          Produce reject files in the specified format (either context
          or unified).  Without this option, rejected hunks come out in
          unified diff format if the input patch was of that format,
          otherwise in ordinary context diff form.

       -s  or  --silent  or  --quiet
          Work silently, unless an error occurs.

       --follow-symlinks
          When looking for input files, follow symbolic links.  Replaces
          the symbolic links, instead of modifying the files the
          symbolic links point to.  Git-style patches to symbolic links
          will no longer apply.  This option exists for backwards
          compatibility with previous versions of patch; its use is
          discouraged.

       -t  or  --batch
          Suppress questions like -f, but make some different
          assumptions: skip patches whose headers do not contain file
          names (the same as -f); skip patches for which the file has
          the wrong version for the Prereq: line in the patch; and
          assume that patches are reversed if they look like they are.

       -T  or  --set-time
          Set the modification and access times of patched files from
          time stamps given in context diff headers.  Unless specified
          in the time stamps, assume that the context diff headers use
          local time.

          Use of this option with time stamps that do not include time
          zones is not recommended, because patches using local time
          cannot easily be used by people in other time zones, and
          because local time stamps are ambiguous when local clocks move
          backwards during daylight-saving time adjustments.  Make sure
          that time stamps include time zones, or generate patches with
          UTC and use the -Z or --set-utc option instead.

       -u  or  --unified
          Interpret the patch file as a unified context diff.

       -v  or  --version
          Print out patch's revision header and patch level, and exit.

       -V method  or  --version-control=method
          Use method to determine backup file names.  The method can
          also be given by the PATCH_VERSION_CONTROL (or, if that's not
          set, the VERSION_CONTROL) environment variable, which is
          overridden by this option.  The method does not affect whether
          backup files are made; it affects only the names of any backup
          files that are made.

          The value of method is like the GNU Emacs `version-control'
          variable; patch also recognizes synonyms that are more
          descriptive.  The valid values for method are (unique
          abbreviations are accepted):

          existing  or  nil
             Make numbered backups of files that already have them,
             otherwise simple backups.  This is the default.

          numbered  or  t
             Make numbered backups.  The numbered backup file name for F
             is F.~N~ where N is the version number.

          simple  or  never
             Make simple backups.  The -B or --prefix, -Y or
             --basename-prefix, and -z or --suffix options specify the
             simple backup file name.  If none of these options are
             given, then a simple backup suffix is used; it is the value
             of the SIMPLE_BACKUP_SUFFIX environment variable if set,
             and is .orig otherwise.

          With numbered or simple backups, if the backup file name is
          too long, the backup suffix ~ is used instead; if even
          appending ~ would make the name too long, then ~ replaces the
          last character of the file name.

       --verbose
          Output extra information about the work being done.

       -x num  or  --debug=num
          Set internal debugging flags of interest only to patch
          patchers.

       -Y pref  or  --basename-prefix=pref
          Use the simple method to determine backup file names (see the
          -V method or --version-control method option), and prefix pref
          to the basename of a file name when generating its backup file
          name.  For example, with -Y .del/ the simple backup file name
          for src/patch/util.c is src/patch/.del/util.c.

       -z suffix  or  --suffix=suffix
          Use the simple method to determine backup file names (see the
          -V method or --version-control method option), and use suffix
          as the suffix.  For example, with -z - the backup file name
          for src/patch/util.c is src/patch/util.c-.

       -Z  or  --set-utc
          Set the modification and access times of patched files from
          time stamps given in context diff headers. Unless specified in
          the time stamps, assume that the context diff headers use
          Coordinated Universal Time (UTC, often known as GMT).  Also
          see the -T or --set-time option.

          The -Z or --set-utc and -T or --set-time options normally
          refrain from setting a file's time if the file's original time
          does not match the time given in the patch header, or if its
          contents do not match the patch exactly.  However, if the -f
          or --force option is given, the file time is set regardless.

          Due to the limitations of diff output format, these options
          cannot update the times of files whose contents have not
          changed.  Also, if you use these options, you should remove
          (e.g. with make clean) all files that depend on the patched
          files, so that later invocations of make do not get confused
          by the patched files' times.

ENVIRONMENT         top

       PATCH_GET
          This specifies whether patch gets missing or read-only files
          from RCS, ClearCase, Perforce, or SCCS by default; see the -g
          or --get option.

       POSIXLY_CORRECT
          If set, patch conforms more strictly to the POSIX standard by
          default: see the --posix option.

       QUOTING_STYLE
          Default value of the --quoting-style option.

       SIMPLE_BACKUP_SUFFIX
          Extension to use for simple backup file names instead of
          .orig.

       TMPDIR, TMP, TEMP
          Directory to put temporary files in; patch uses the first
          environment variable in this list that is set.  If none are
          set, the default is system-dependent; it is normally /tmp on
          Unix hosts.

       VERSION_CONTROL or PATCH_VERSION_CONTROL
          Selects version control style; see the -v or --version-control
          option.

FILES         top

       $TMPDIR/p*
          temporary files

       /dev/tty
          controlling terminal; used to get answers to questions asked
          of the user

SEE ALSO         top

       diff(1), ed(1), merge(1).

       Marshall T. Rose and Einar A. Stefferud, Proposed Standard for
       Message Encapsulation, Internet RFC 934
       <URL:ftp://ftp.isi.edu/in-notes/rfc934.txt> (1985-01).

NOTES FOR PATCH SENDERS         top

       There are several things you should bear in mind if you are going
       to be sending out patches.

       Create your patch systematically.  A good method is the command
       diff -Naur old new where old and new identify the old and new
       directories.  The names old and new should not contain any
       slashes.  The diff command's headers should have dates and times
       in Universal Time using traditional Unix format, so that patch
       recipients can use the -Z or --set-utc option.  Here is an
       example command, using Bourne shell syntax:

              LC_ALL=C TZ=UTC0 diff -Naur gcc-2.7 gcc-2.8

       Tell your recipients how to apply the patch by telling them which
       directory to cd to, and which patch options to use.  The option
       string -Np1 is recommended.  Test your procedure by pretending to
       be a recipient and applying your patch to a copy of the original
       files.

       You can save people a lot of grief by keeping a patchlevel.h file
       which is patched to increment the patch level as the first diff
       in the patch file you send out.  If you put a Prereq: line in
       with the patch, it won't let them apply patches out of order
       without some warning.

       You can create a file by sending out a diff that compares
       /dev/null or an empty file dated the Epoch (1970-01-01 00:00:00
       UTC) to the file you want to create.  This only works if the file
       you want to create doesn't exist already in the target directory.
       Conversely, you can remove a file by sending out a context diff
       that compares the file to be deleted with an empty file dated the
       Epoch.  The file will be removed unless patch is conforming to
       POSIX and the -E or --remove-empty-files option is not given.  An
       easy way to generate patches that create and remove files is to
       use GNU diff's -N or --new-file option.

       If the recipient is supposed to use the -pN option, do not send
       output that looks like this:

              diff -Naur v2.0.29/prog/README prog/README
              --- v2.0.29/prog/README   Mon Mar 10 15:13:12 1997
              +++ prog/README   Mon Mar 17 14:58:22 1997

       because the two file names have different numbers of slashes, and
       different versions of patch interpret the file names differently.
       To avoid confusion, send output that looks like this instead:

              diff -Naur v2.0.29/prog/README v2.0.30/prog/README
              --- v2.0.29/prog/README   Mon Mar 10 15:13:12 1997
              +++ v2.0.30/prog/README   Mon Mar 17 14:58:22 1997

       Avoid sending patches that compare backup file names like
       README.orig, since this might confuse patch into patching a
       backup file instead of the real file.  Instead, send patches that
       compare the same base file names in different directories, e.g.
       old/README and new/README.

       Take care not to send out reversed patches, since it makes people
       wonder whether they already applied the patch.

       Try not to have your patch modify derived files (e.g. the file
       configure where there is a line configure: configure.in in your
       makefile), since the recipient should be able to regenerate the
       derived files anyway.  If you must send diffs of derived files,
       generate the diffs using UTC, have the recipients apply the patch
       with the -Z or --set-utc option, and have them remove any
       unpatched files that depend on patched files (e.g. with
       make clean).

       While you may be able to get away with putting 582 diff listings
       into one file, it may be wiser to group related patches into
       separate files in case something goes haywire.

DIAGNOSTICS         top

       Diagnostics generally indicate that patch couldn't parse your
       patch file.

       If the --verbose option is given, the message Hmm... indicates
       that there is unprocessed text in the patch file and that patch
       is attempting to intuit whether there is a patch in that text
       and, if so, what kind of patch it is.

       patch's exit status is 0 if all hunks are applied successfully, 1
       if some hunks cannot be applied or there were merge conflicts,
       and 2 if there is more serious trouble.  When applying a set of
       patches in a loop it behooves you to check this exit status so
       you don't apply a later patch to a partially patched file.

CAVEATS         top

       Context diffs cannot reliably represent the creation or deletion
       of empty files, empty directories, or special files such as
       symbolic links.  Nor can they represent changes to file metadata
       like ownership, permissions, or whether one file is a hard link
       to another.  If changes like these are also required, separate
       instructions (e.g. a shell script) to accomplish them should
       accompany the patch.

       patch cannot tell if the line numbers are off in an ed script,
       and can detect bad line numbers in a normal diff only when it
       finds a change or deletion.  A context diff using fuzz factor 3
       may have the same problem.  You should probably do a context diff
       in these cases to see if the changes made sense.  Of course,
       compiling without errors is a pretty good indication that the
       patch worked, but not always.

       patch usually produces the correct results, even when it has to
       do a lot of guessing.  However, the results are guaranteed to be
       correct only when the patch is applied to exactly the same
       version of the file that the patch was generated from.

COMPATIBILITY ISSUES         top

       The POSIX standard specifies behavior that differs from patch's
       traditional behavior.  You should be aware of these differences
       if you must interoperate with patch versions 2.1 and earlier,
       which do not conform to POSIX.

        In traditional patch, the -p option's operand was optional,
          and a bare -p was equivalent to -p0.  The -p option now
          requires an operand, and -p 0 is now equivalent to -p0.  For
          maximum compatibility, use options like -p0 and -p1.

          Also, traditional patch simply counted slashes when stripping
          path prefixes; patch now counts pathname components.  That is,
          a sequence of one or more adjacent slashes now counts as a
          single slash.  For maximum portability, avoid sending patches
          containing // in file names.

        In traditional patch, backups were enabled by default.  This
          behavior is now enabled with the -b or --backup option.

          Conversely, in POSIX patch, backups are never made, even when
          there is a mismatch.  In GNU patch, this behavior is enabled
          with the --no-backup-if-mismatch option, or by conforming to
          POSIX with the --posix option or by setting the
          POSIXLY_CORRECT environment variable.

          The -b suffix option of traditional patch is equivalent to the
          -b -z suffix options of GNU patch.

        Traditional patch used a complicated (and incompletely
          documented) method to intuit the name of the file to be
          patched from the patch header.  This method did not conform to
          POSIX, and had a few gotchas.  Now patch uses a different,
          equally complicated (but better documented) method that is
          optionally POSIX-conforming; we hope it has fewer gotchas.
          The two methods are compatible if the file names in the
          context diff header and the Index: line are all identical
          after prefix-stripping.  Your patch is normally compatible if
          each header's file names all contain the same number of
          slashes.

        When traditional patch asked the user a question, it sent the
          question to standard error and looked for an answer from the
          first file in the following list that was a terminal: standard
          error, standard output, /dev/tty, and standard input.  Now
          patch sends questions to standard output and gets answers from
          /dev/tty.  Defaults for some answers have been changed so that
          patch never goes into an infinite loop when using default
          answers.

        Traditional patch exited with a status value that counted the
          number of bad hunks, or with status 1 if there was real
          trouble.  Now patch exits with status 1 if some hunks failed,
          or with 2 if there was real trouble.

        Limit yourself to the following options when sending
          instructions meant to be executed by anyone running GNU patch,
          traditional patch, or a patch that conforms to POSIX.  Spaces
          are significant in the following list, and operands are
          required.

             -c
             -d dir
             -D define
             -e
             -l
             -n
             -N
             -o outfile
             -pnum
             -R
             -r rejectfile

BUGS         top

       Please report bugs via email to <bug-patch@gnu.org>.

       If code has been duplicated (for instance with #ifdef OLDCODE ...
       #else ... #endif), patch is incapable of patching both versions,
       and, if it works at all, will likely patch the wrong one, and
       tell you that it succeeded to boot.

       If you apply a patch you've already applied, patch thinks it is a
       reversed patch, and offers to un-apply the patch.  This could be
       construed as a feature.

       Computing how to merge a hunk is significantly harder than using
       the standard fuzzy algorithm.  Bigger hunks, more context, a
       bigger offset from the original location, and a worse match all
       slow the algorithm down.

COPYING         top

       Copyright (C) 1984, 1985, 1986, 1988 Larry Wall.
       Copyright (C) 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
       1997, 1998, 1999, 2000, 2001, 2002, 2009 Free Software
       Foundation, Inc.

       Permission is granted to make and distribute verbatim copies of
       this manual provided the copyright notice and this permission
       notice are preserved on all copies.

       Permission is granted to copy and distribute modified versions of
       this manual under the conditions for verbatim copying, provided
       that the entire resulting derived work is distributed under the
       terms of a permission notice identical to this one.

       Permission is granted to copy and distribute translations of this
       manual into another language, under the above conditions for
       modified versions, except that this permission notice may be
       included in translations approved by the copyright holders
       instead of in the original English.

AUTHORS         top

       Larry Wall wrote the original version of patch.  Paul Eggert
       removed patch's arbitrary limits; added support for binary files,
       setting file times, and deleting files; and made it conform
       better to POSIX.  Other contributors include Wayne Davison, who
       added unidiff support, and David MacKenzie, who added
       configuration and backup support.  Andreas Grünbacher added
       support for merging.

COLOPHON         top

       This page is part of the patch (GNU patch) project.  Information
       about the project can be found at 
       ⟨http://savannah.gnu.org/projects/patch/⟩.  If you have a bug
       report for this manual page, see
       ⟨http://savannah.gnu.org/bugs/?group=patch⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨git://git.savannah.gnu.org/patch.git⟩ on 2021-04-01.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-01-08.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

GNU                                                             PATCH(1)

Pages that refer to this page: diff(1)gendiff(1)suffixes(7)